c#:自动出题并判分，源代码

int a, b;

string op;

int result;

Random rnd = new Random();

private void btnNew_Click(object sender, System.EventArgs e)

{

a = rnd.Next( 9 ) + 1;

b = rnd.Next( 9 ) + 1;

int c = rnd.Next( 4 );

switch( c )

{

case 0: op="+"; result=a+b; break;

case 1: op="-"; result=a-b; break;

case 2: op="*"; result=a*b; break;

case 3: op="/"; result=a/b; break;

}

lblA.Text=a.ToString();

lblB.Text=b.ToString();

lblOp.Text=op;

txtAnswer.Text="";

}

private void btnJudge_Click(object sender, System.EventArgs e)

{

string str = txtAnswer.Text;

double d = double.Parse( str );

string disp = "" + a + op + b+"="+ str +" ";

if( d == result ) // if( Math.Abs(d-result)< 1e-3 )

disp += "☆";

else

disp += "╳";

lstDisp.Items.Add( disp );

}

}